STUDIES ON THE PARTITIONING OF ACTINIDES FROM HIGH LEVEL WASTE USING A MIXTURE OF HDEHP AND CMPO AS EXTRACTANT

The paper describes the extraction and stripping behavior of actinides and lanthanides viz. americium, plutonium, uranium, cerium, and europium using a mixture of di-(2-ethylhexyl)phosphoric acid (HDEHP) and octyl(phenyl)-N,N-diisobutylcarbamoyl- methylphosphine oxide (CMPO) in n-paraffin as extractant. The extractant mixture combines the advantages of both the extractants for the partitioning of actinides from PUREX High Level Waste (HLW) solution. The extraction studies have been carried out from nitric acid medium as well as with simulated uranium-lean PUREX-HLW solution as relevant to Pressurized Heavy Water Reactor (PHWR) fuel reprocessing. The extracted actinides are stripped using a mixture of diethylenetriaminepentaacetic acid (DTPA), formic acid and hydrazine hydrate, leaving lanthanides in the organic phase. The lanthanides are subsequently stripped using a mixture of DTPA and sodium carbonate. The behavior of cesium, strontium, ruthenium, and zirconium is also studied using this mixed extractant.